66

I'm a programmer and private pilot, so maybe I can help dispel some of those fears. The computers that run a commercial airplane are conceptually much simpler than the one that runs your phone. This means far less chance of a bug in the software, just because there's less for the programmer to keep track of. If your phone restarts, it doesn't imperil ...


57

If no, why not? While I can't say categorically that it's not happened, I'm pretty sure. Solar radiance is approx. 1kW/m^2. A 737 has approximately 100m^2 wing area. Solar cells are approximately 20% effective. If you covered the entire wings in solar panels, that would work out to 20kW of electrical power at best. At night, it would be close to zero ...


33

It's the second option. In any other context, a small aircraft's electrical system would be called "24V". But the alternator regularly puts out 28V, so that's what's typically expected if you hook up your multimeter while the engine's running. Of course, the on-board equipment can operate over a wide range of voltages, often down to as little as 20V.


30

Stays where it is. The mechanism is a leadscrew and like most leadscrews it's "self-locking", which means that it's held in position by frictional forces whenever the motor isn't turning and it can't be back-driven even by substantial loads. The 20 degree (etc) "stops" are just reference positions for which aircraft performance and load limit data have been ...


25

Multiple sources indicate that the 28 VDC bus on aircraft powered by 24 VDC batteries, and the 24 VDC systems on truck powered by 28 VDC alternators, are basically the same thing, and that is is just a naming convention. The number of cells is a function of the nominal voltage and the cell type. From this site: Lead Acid: 2 volts/cell Nickel based for ...


24

Before we start, it's important to say that your concern is not irrational. If this were to happen, or if your plane's control systems were to otherwise malfunction in a dangerous manner, your life would genuinely be in danger. You aren't the first person to have thought of this, though. For this reason, we have a category of control systems we describe ...


23

Other than the APU, there are multiple ways to provide electrical power to an aircraft: Battery: The battery is typically the first thing you would turn on and it usually provides DC power to emergency systems only (at least on an airliner, smaller aircraft are fully powered by the battery). Running only on battery power will however deplete the battery ...


19

Cable is not just the metal wire. It's also insulation, installation, cable channels, extra space at tight bends where cable flexibility is insufficient, and maintenance of said cable. Aluminum corrodes in a lot of conditions and happens to be one of the most fatigue-susceptible metals. For these reasons, most aircraft wiring is copper and silver-plated or ...


16

Let me start of with two facts that pretty much answer your question: A 24V battery is a battery that can output at least 24V over the majority of its capacity. To charge a rechargeable battery you need to push charge into it by providing it with a higher voltage than what the battery is currently at. To put a bit more meat on, here is a typical discharge ...


15

Onboard batteries for DC and a ground power supply for AC. The ground supply can come either from an airport vehicle or from the stand itself. Since the standard AC in aviation is 115V and 400Hz, the usual ground power supply needs to be converted to a higher frequency. This used to be done with a rotating converter, i.e. a motor (at 110V and 60Hz or ...


11

No, there are several reasons: Fragility v Efficiency v Weight: the most efficient solar panels are rigid and heavy, which is bad for a wing structure. Flexible and light panels do exist, but they are half the efficiency. They also have limitations to how much flexing they really can take, the constant flexing of a wing, vibrations, cycles between hot and ...


10

Your concerns are reasonable and justified. A mid-air shutdown or reboot would be catastrophic to an airliner. Which is why, engineers designed the systems such that this scenario is practically impossible to happen. Electrical power An airliner has multiple electrical power source. Each jet engine has a built-in generator. When the turbine spins, ...


6

According this rather detailed page on the 727's engines: To restart in flight, an "air start" may be attempted. The start switch should be placed in the FLIGHT START position which will arm high energy ignition. The starter valve will not open. Ram air entering the engine is sufficient for start if the aircraft's speed is above 150 knots. When ...


4

As I understand it (I'm neither an F-16 pilot nor an F-16 mechanic), Relaxed Static Stability doesn't mean the aircraft is unstable, just that it's less stable than the long-established standard. To put it another way, if you build a free flight model airplane scaled from an F-16, you'll have to put the center of mass significantly further forward than its ...


4

as somebody who did software tests on an unimportant (class D, will explain soon) system for an airplane to be approved to be landed on civilian airports: In airplane there is a strict hierarchy on what kind of software functions mean; they are listed in DO-178B. Class A systems are assumed to be "failure free"; they are extremely well tested. These ...


4

Occasionally a computer or smartphone will crash and reboot itself This can happen for two reasons: a software error or a hardware error. Both can cause the CPU to stop processing new instructions (i.e. a "hang") or to cause the machine to reboot itself. The latter is close to a hang, because the Operating System detects it cannot continue operating ...


4

What's the plug pair called? I don't think there's an "official" name for it, but it's usually referred to as the "ground power connection" or something similar. Also, there's usually only one connection; only the biggest commercial aircraft need two connections simply because one connection can't supply enough power. What's the ISO/whatever standard ...


4

But in reality, the fully charged/charging/float voltage of the system with alternator running is higher Yes. If a car battery states 12V that's kind-of the lower limit. As in, it really shouldn't drop below 11.8 when fully discharged, although depending on the type of battery and vehicle it may still function (for some values of function). A fully charged ...


4

Different aircraft and manufacturers take very different approaches. 1. Boeing 777 The B777 has three Primary Flight Computers (PFC) that are responsible for flight control laws computation and four Actuator Control Units (ACE) that are responsible for the closed-loop control of their responsible flight control surfaces. The ACE is primarily an analog ...


3

Yes it loads up the battery, but the battery is sized to do this. The generator is not necessarily sized to do this, especially on the ground, so this procedure gets you to take the generator out of the system for each start. On an Alternator, like on your car, there is a phenomenon known as 'forward-stripping', which is where there is such a demand for ...


3

You are getting the APU mixed up with the RAT: The Auxiliary Power Unit (APU) is an engine powered generator, either a gas turbine or a piston engine. APUs deliver enough power to start engines, power cabin lights, cockpit instruments and radios, and in some cases power hydraulics. Often the APU can only be run at lower altitudes where the air is thicker A ...


2

A VFG on a A350 (Variable Freq Generator) ranges from 360Hz to 800Hz (idle to takeoff) but it weighs less than a traditional IDG or CDS due to the fact that it has less components inside since it does not need to convert the freq to a fixed 400Hz. Most components that use AC convert the variable frequency to a fixed 400Hz anyway. The output of the ...


2

Every now and then I get to fly two DH82a Tiger Moth that are retro fitted with batteries and alternators to provide power for the radio and transponder as this type originally was not fitted with any electronic systems -- along a few other things e.g. brakes, tailwheel, flaps, a reasonably-sized windscreen, adjustable seats, some useful avionics and of ...


2

The better way to think of it is this: the electrical system of an aircraft is not battery powered at all. It is powered by engine driven generators or alternators. These devices provide all the electrical power used while the aircraft is operating in the air or on the ground. However, when the engine(s) isn't/aren't running, electrical power is needed to ...


2

Cessna Cardinals used it to connect battery in the tail to where ever if goes up front. The ends were properly terminated and treated to prevent dissimilar metal corrosion. My 1973 plane is still flying with it.


2

You can't easily link the two AC buses together, you'd need to synchronize the phases first. And then a short on one side could cause a complete failure so you'd have to isolate them again. Way to complicated to get that failure tolerant. Instead they just use two independent AC systems. Generally each system exists twice and each one gets a different power ...


2

I once worked for a company that made electronics for commercial aircraft (flight deck printers, Ethernet switches, digital chart recorders). In addition to what others have mentioned on this thread, you also have to account for the fact that if a product is manufactured for aircraft in the US, it must comply AS9100 and FAR, and whatever standard the EU is ...


2

Not purely on topic but there is a solar airplane. Solar supported airliner isn't out of the realm of possibilities, just solar tech isn't there yet. Also it would have to be economically feasible to even be considered. Here's an article from 2016 about a solar airplane that traveled the globe. https://www.theguardian.com/environment/2016/jul/26/solar-...


2

You need power for lighting, fans, intercom, and CVR/flight recorder, cameras; any and all of them are required for towing an aircraft, depending upon its size, and in the event of an accident. See: "Aircraft Towing": Accidents and Incidents "B763, Luton UK, 2005 (On 16 February 2005, at Luton Airport, a Boeing B767-300 collided with the tug pulling it ...


2

Worked at an airport for 3 years. Aircraft were either powered by battery, GPU, jet bridge, or engines. But being powered by engines presented a problem, in that all the blast zones would be deadly and severely limit what work can be done on the aircraft, if any. Generally the procedure was to get the ground power connected as soon as the aircraft was ...


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